Thick film capacitor

ABSTRACT

Disclosed is a thick film capacitor comprising (a) a sintered layer of a ferroelectric material mainly consisting of one or more ferroelectric inorganic compounds having a perovskite structure and an inorganic binder having a eutectic composition which experiences a liquid phase at a temperature lower than the sintering temperature of the ferroelectric inorganic compounds, and (b) at least two electrodes formed on both surfaces of the sintered layer of the ferroelectric material. In the thick film capacitor of this invention, the perovskite structure of the ferroelectric inorganic compounds is not destroyed upon sintering. Therefore, a high degree of sintering, a good dielectric characteristic and high moisture and migration resistances can be obtained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thick film capacitor.

2. Description of the Prior Art

A thick film capacitor has a structure wherein a sintered layer offerroelectric materials is sandwiched between metal electrodes.Ferroelectric compounds used for the thick film capacitor normally havea poor degree of sintering, and it is very difficult to constitute asintered layer solely by the ferroelectric compounds. For this reason,in the conventional thick film capacitor, a crystalline or amorphousglass is added as a binder to perform sintering, thereby forming thesintered layer of the ferroelectric materials.

However, the addition of glass remarkably degrades the dielectriccharacteristic of the sintered layer of ferroelectric materials. Forexample, when a commercially available crystalline or amorphous glass isadded to ferroelectric inorganic compounds having a dielectric constantof 20,000 and the mixture is sintered, the dielectric constant of theresultant sintered layer of ferroelectric materials is considerablydegraded to 100 to 1000, i.e., a value 1/20 to 1/200 the value beforesintering. This is because, upon sintering with a glass additive, theperovskite structure of the ferroelectric inorganic compounds isdestroyed.

Since the conventional thick film capacitor contains glass in thesintered layer of ferroelectric materials, it has poor moistureresistance. The conventional capacitor easily causes migration ofelectrode metals, i.e., has a poor migration resistance.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a thick filmcapacitor which has a high degree of sintering, a good dielectriccharacteristic and a high moisture resistance, and can effectivelyprevent migration of electrode metals.

In order to achieve the object of the present invention, a thick filmcapacitor comprises:

(a) a sintered layer of a ferroelectric material mainly consisting ofone or more ferroelectric inorganic compounds having a perovskitestructure and an inorganic binder having a eutectic composition whichexperiences a liquid phase at the temperature lower than a sinteringtemperature of the ferroelectric inorganic compounds; and

(b) at least two electrodes formed on both surfaces of the sinteredlayer of the ferroelectric material.

The inorganic binder contained in the sintered layer of ferroelectricmaterial functions as a binder at a temperature at which the perovskitestructure of the respective ferroelectric inorganic compound is notdestroyed. For this reason, the ferroelectric compounds in the sinteredlayer can retain the original perovskite structure. As a result, a highdegree of sintering, a good dielectric characteristic and a highmoisture resistance can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a thick film capacitor according toan embodiment of the present invention;

FIG. 2 is a sectional view showing a state before sintering of a thickfilm capacitor according to another embodiment of the present invention;

FIG. 3 is a sectional view showing a thick film capacitor according tostill another embodiment of the present invention; and

FIGS. 4 and 5 are graphs for comparing the influences of aging at hightemperature between a thick film capacitor according to an embodiment ofthe present invention and a conventional thick film capacitor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Examples of ferroelectric inorganic compounds constituting a sinteredlayer of ferroelectric materials in a thick film capacitor of thepresent invention include those shown in Table 1. Among these compounds,the following compounds are particularly preferable:

Pb(Fe_(1/2) Nb_(1/2))O₃ -Ba(Cu_(1/2) W_(1/2))O₃,

BaTiO₃, PbTiO₃, and

(Pb,X){(Zn_(1/3) Nb_(2/3))(Mg_(1/3) Nb_(2/3))Ti}O₃ ;

X=Ba, Ca, Sr, La.

                  TABLE 1                                                         ______________________________________                                        No.  Abbreviation                                                                             General Formula                                               ______________________________________                                         1   PFN        Pb(Fe.sub.1/2 Nb.sub.1/2)O.sub.3                               2   BCW        Ba(Cu.sub.1/2 W.sub.1/2)O.sub.3                                3   PBZMT      (Pb.sub.0.8 Ba.sub.0.2) (Zn.sub.1/3 Nb.sub.2/3).sub.0.85                      Ti.sub.0.15 O.sub.3                                            4   PMZFW      Pb(Mg.sub.1/3 Nb.sub.2/3).sub.0.3 (Zn.sub.1/3 Nb.sub.2/3).                    sub.0.4 (Fe.sub.2/3 W.sub.1/3).sub.0.3 O.sub.3                 5   PNiWFN     Pb(Ni.sub.1/2 W.sub.1/2).sub.0.1 (Fe.sub.1/2 Nb.sub.1/2).s                    ub.0.9 O.sub.3                                                 6   BTZ        BaTi.sub.0.89 Zr.sub.0.11 O.sub.3                              7   PZNFWNi    Pb(Zn.sub.1/2 Nb.sub.1/2).sub.0.3 (Fe.sub.2/3 W.sub.1/3).s                    ub.0.4 (Ni.sub.1/3 Nb.sub.2/3).sub.0.3 O.sub.3                 8   PCoW       Pb(Co.sub.1/2 W.sub.1/2)O.sub.3                                9   PNiNFW     Pb(Ni.sub.1/3 Nb.sub.2/3).sub.0.1 (Fe.sub.1/2 Nb.sub.1/2).                    sub.0.6 (Fe.sub.2/3 W.sub.1/3).sub.0.3 O.sub.3                10   PT         PbTiO.sub.3                                                   11   PMN        Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                              12   PBMNT      (Pb.sub.0.7 Ba.sub.0.3)(Mg.sub.1/3 Nb.sub.2/3 Ti)O.sub.3      13   PZN        Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3                              14   PCaMNNiW   (PbCa.sub.0.03){(Mg.sub.1/3 Nb.sub.2/3).sub.0.7 Ti.sub.0.2                     (Ni.sub.1/2 W.sub.1/2).sub.0.1 }O.sub.3.03                   15   SPT        Sr.sub.0.05 Pb.sub.0.95 TiO.sub.3                             16   PMW        Pb(Mg.sub.1/2 W.sub.1/2)O.sub.3                               17   PFW        Pb(Fe.sub.2/3 W.sub.1/3)O.sub.3                               18   PMnTa      Pb(Mn.sub.1/3 Ta.sub.2/3)O.sub.3                              19   PMnN       Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3                              20   PZr        PbZrO.sub.3                                                   21   PMnW       Pb(Mn.sub.1/2 W.sub.1/2)O.sub.3                               22   PNiN       Pb(Ni.sub.1/3 Nb.sub.2/3)O.sub.3                              23   PNiW       Pb(Ni.sub.1/2 W.sub.1/2)O.sub.3                               24   PMnSb      Pb(Mn.sub.1/3 Sb.sub.2/3)O.sub.3                              25   PCZMT      (PbCa){(Zn.sub.1/3 Nb.sub.2/3).sub.0.3 (Mg.sub.1/3                            Nb.sub.2/3).sub.0.5 Ti.sub.0.2 }O.sub.3                       ______________________________________                                    

In this invention, examples of inorganic binders included in thesintered layer of ferroelectric materials include the following binarymixtures of oxides:

PbO-CuO, PbO-WO₃, PbO-Nb₂ O₅, PbO-Fe₂ O₃,

PbO-ZnO, PbO-TiO₂, PbO-CaO, PbO-Sb₂ O₃,

BaO-WO₃, Nb₂ O₃ -TiO₂, TiO₂ -MgO, PbO-MgO, and etc.

Note that mixtures containing three or more oxides can be also used.Further, compounds which are converted to the above oxides duringsintering, e.g., nitrides, halides, or organometallic compounds, can beused as the inorganic binder in the present invention.

The inorganic binder has a eutectic composition which produces a liquidphase at a temperature lower than the sintering temperature of theferroelectric inorganic compounds having the perovskite structure, andallows the liquid phase over a wide composition range. Therefore, theinorganic binder can promote the sintering of the ferroelectricinorganic compounds without changing the perovskite structure of thecompounds. The inorganic binder of the present invention promotesshrinkage of the ferroelectric inorganic compounds upon sintering toprovide a dense composition and to stabilize sintering. For this reason,the sintered layer of ferroelectric materials in the present inventionhas a good dielectric characteristic equivalent to that of theferroelectric inorganic compounds itself, and has high moisture andmigration resistances.

The inorganic binder consisting of the above mixture can be directlyadded to the ferroelectric inorganic compounds after the respectivecomponents are mixed. The binder can be added after pre-sintering isperformed, as needed.

A pair of electrodes in the present invention are formed by printing ametal paste selected from the group consisting of, e.g., Au, Ag, Ag-Pd,Pt, Ag-Pt, Cu, Ni, Pd, W, and the like and sintering the paste layer. Inthe preferred embodiment of the present invention, one (2a) of the pairof electrodes is formed on insulating substrate 1 such as an aluminasubstrate, and sintered layer 3 of ferroelectric material having theabove-mentioned composition and the other electrode 2b are sequentiallyformed thereon, as shown in FIG. 1. As shown in FIG. 3, sintered layer3' of ferroelectric materials in which a predetermined amount of theabove inorganic binder is added can be interposed between insulatingsubstrate 1 and lower electrode 2a. With this structure, the adhesionstrength between electrode 2a and substrate 1 can be improved comparedto the structure wherein electrode 2a is directly formed on substrate 1.

A method of manufacturing a thick film capacitor of the presentinvention will now be illustrated below.

First, ferroelectric inorganic compounds as shown in Table 1 areprepared. For this purpose, raw materials are formulated to prepare acomposition corresponding to an respective individual ferroelectricinorganic compound, and thereafter, pre-sintering and the like isperformed to synthesize the ferroelectric inorganic compounds. Theinorganic compounds need not always include 100% perovskite phase.

Components of an inorganic binder of the present invention areformulated to obtain a predetermined eutectic composition, and thecomposition is mixed with the above ferroelectric inorganic compounds.At this time, the mixing ratio differs depending on the types offerroelectric inorganic compounds and inorganic binder, and cannot beuniquely limited. Generally, if the binder amount is too much, thedielectric characteristic of the sintered layer is degraded; otherwise,if the binder amount is too little, a sufficient degree of sinteringcannot be obtained. Therefore, the mixing ratio must be set to obtainsintered layer of a ferroelectric materials having a good dielectriccharacteristic and a high degree of sintering.

The resultant mixture is ground to have a predetermined particle size,and a solvent and an organic binder are added thereto, thereby preparinga ferroelectric paste. If an average particle size of the ground mixtureis 1.0 μm or less, it is difficult to grow crystal grains uponsintering, and this causes a decrease in the dielectric constant. If theaverage particle size exceeds 10 μm, printing of the preparedferroelectric paste may be disturbed. Therefore, the average particlesize should preferably fall within the range of 1.0 to 10 μm. A solventfor preparing the ferroelectric paste can be a normally used solventsuch as terpineol, methyl ethyl cellosolve, n-butanol, or the like. Theorganic binder can be a binder normally used for ceramic molding, suchas ethyl-cellulose, methyl-cellulose, polyacryl-resin, polystyrene,polyurethane, polyvinyl alcohol, polyvinyl butyral, nitrocellulose, orthe like.

The above-mentioned metal paste and the ferroelectric paste arealternately printed on the insulating substrate, so that a metal pastelayer, a ferroelectric paste layer, and another metal paste layer arestacked in this order. Thereafter, the resultant multi-layered structureis sintered. Thus, thick film capacitor 4, wherein metal electrodes 2aand 2b are disposed on and under sintered layer 3 of the ferroelectricmaterials, can be formed, as shown in FIG. 1. The sintering temperatureat this time varies depending upon the metal paste and the ferroelectricpaste used. Generally, the sintering temperature falls within a rangewithin which neither swelling nor peeling of other resistors, wirings,and the like occurs. In the above description, the paste layers aresintered at the same time. However, the printing and sintering can berepeated to sequentially form layers 2a, 3, and 2b.

When the thick film capacitor is manufactured by the above method, theinorganic binder is in a liquid phase, and its function as a binder isdeveloped. After sintering, the inorganic binder forms a bonding layerat the grain boundaries of the ferroelectric inorganic compounds, or isdiffused in the crystal lattices of the ferroelectric inorganiccompounds. However, it has been confirmed that even when the inorganicbinder of the present invention is diffused in the crystal lattices ofthe ferroelectric inorganic compound, it does not destroy the perovskitestructure of the ferroelectric compound unlike glass used in aconventional method. As a result, with the above-mentioned method, athick film capacitor having a high degree of sintering, a gooddielectric characteristic, and high moisture and migration resistancescan be obtained.

Another manufacturing method will now be illustrated. In thisembodiment, a second ferroelectric paste having the same composition asthat of the above-mentioned ferroelectric paste, except that noinorganic binder is added thereto, is prepared. Using the secondferroelectric paste, the above-mentioned ferroelectric paste, and themetal paste, metal paste layer 12a, ferroelectric paste layer 13a,second ferroelectric paste layer 14, ferroelectric paste layer 13b, andmetal paste layer 12b are sequentially printed and stacked, as shown inFIG. 2. When the structure in the state shown in FIG. 2 is sintered,paste layers 12a, 13a, 14, 13b, and 12b are sintered and the inorganicbinder contained in layers 13a and 13b is diffused in secondferroelectric paste layer 14. For this reason, although secondferroelectric paste layer 14 does not originally contain the inorganicbinder, a good sintered state can be obtained due to diffusion of theinorganic binder during sintering. In addition, since the resultantsecond sintered layer has a smaller content of the inorganic binder thanthat of the upper and lower sintered layers, it has a good dielectriccharacteristic. Therefore, in this embodiment, since the second sinteredlayer of the ferroelectric materials is included, a thick film condenserhaving a superior dielectric characteristic to that shown in FIG. 1 canbe obtained. In this embodiment, the sintering process may be performedbefore stacking the next paste layer, so that respective paste layers12a, 13a, 14, 13b, and 12b are separately sintered.

Still another embodiment will now be described with reference to FIG. 3.In this embodiment, a ferroelectric paste layer, a metal paste layer, aferroelectric paste layer, and another metal paste layer aresequentially printed and stacked on insulating substrate 1. Then, theresultant structure is sintered, and is cut into desired sizes. Thus,tip capacitor 5, in which sintered layers 3a and 3b of ferroelectricmaterials and electrodes 2a and 2b are alternately stacked, can bemanufactured, as shown in FIG. 3. As has been described above,ferroelectric layer 3a has a function of improving the mechanicalbonding strength between insulating substrate 1 and electrode 2a. Notethat the tip capacitor shown in FIG. 3 is constituted by two layers ofelectrodes 2a and 2b, and two ferroelectric layers 3a and 3b. Tipcapacitors in which a still lager number of electrodes and ferroelectriclayers are stacked can be similarly produced. Electrodes 2a and 2b andferroelectric layers 3a and 3b may be sequentially printed and sinteredin place of simultaneous sintering.

The method of manufacturing the tip capacitor according to the aboveillustration has the following advantage as compared to a case wherein atip capacitor is manufactured by the green sheet method. With the greensheet method, a special tool for supporting a multilayered sheet isnecessary. However, in the above embodiment, insulating substrate 1 hasa support function, and no special tool is required. The number ofprocesses can be reduced. In addition, a thick-film belt-furnace can beused for degreasing and sintering, and production can be completedwithin a short period of time.

In the manufacturing method of the present invention, aging at hightemperature is preferably performed for the resultant sintered product.In the case of this invention, with this aging at high temperature, adielectric characteristic such as a dielectric constant, a dissipationfactor (tanδ10⁻²), a volume resistivity, and the like can be improved.This is quite different from the fact that in a conventional thick filmcapacitor using a glass binder, the similar aging at high temperaturedegrades the dielectric characteristics. This is because glass destroysthe perovskite structure of the sintered layer of ferroelectricmaterials during aging at high temperature, while, in the presentinvention, the above-mentioned inorganic binder does not damage theperovskite structure of the sintered layer of ferroelectric materialsbut rather promotes its crystal growth. In order to obtain this effect,an upper temperature of aging must be determined so as not to causevoids, swelling, melting, and the like of the ferroelectric layers andelectrodes, and a lower temperature limit must be determined to enablethe inorganic binder components to diffuse sufficiently into theferroelectric compounds.

Examples of the present invention will be explained hereinafter.

EXAMPLES 1-16 <A> Synthesis of Ferroelectric Inorganic Compounds

As starting materials, PbO, Fe₂ O₃, WO₃, Nb₂ O₅, BaCO₃, CuO, MgCO₃, andNiO were used and were formulated to obtain compositions correspondingto ferroelectric compounds PFN and BCW shown in Table 1. The PFN and BCWformulas, and NiO, MgO, and MnO as additives were formulated at molarratios shown in Table 2. In this formulation, mixing ratios of PFN andBCW were adjusted so that x and y in the following formula satisfyx+y=1:

    x(PFN)-y(BCW)

Subsequently, the formulated raw materials were wet-mixed by a ballmill, and the mixtures were pre-sintered at a temperature of 700° to800° C. Furthermore, the resultant sintered structures were ground anddried, thereby preparing ferroelectric inorganic compounds.

<B> Preparation of Inorganic Binder

As raw materials, PbO, CuO, and WO₃ were used, and were weighed toobtain molar ratios shown in Table 2. These materials were wet-mixed bya ball mill and dried, thereby obtaining eutectic compositions PbO-CuOand PbO-WO₃. The eutectic compositions were pre-sintered at atemperature of 600° to 830° C. Thereafter, the pre-sintered compositionswere ground by a ball mill and were dried and used as inorganic binders.

<C> Preparation of Ferroelectric Paste

The ferroelectric inorganic compounds and inorganic binders prepared inprocesses <A> and <B> were formulated at ratios shown in Table 2. 28% byweight of terpineol as a solvent and 4% by weight of ethyl-cellulose asan organic binder were added to 68% by weight of each formula and weremixed, thus preparing 16 types of ferroelectric pastes.

<D> Manufacture of Thick Film Capacitor

Thick film capacitors as shown in FIG. 1 were produced using theferroelectric pastes as follows. An Ag-Pb-based metal paste was printedon a 2"×2" alumina substrate, and the above ferroelectric pastes wereprinted and stacked thereon. Furthermore, another Ag-Pb-based metalpaste was printed and stacked on the ferroelectric paste layer of thestructure, and thereafter, the resultant structure was sintered at 900°C. for 10 minutes using a belt oven.

The dielectric constant and dissipation factor (tanδ×10⁻²) at 1 kHz ofthe resultant thick film capacitors were measured. The results shown inTable 2 were obtained.

Note that for the sake of comparison, conventional thick film capacitorsusing glass as an inorganic binder were manufactured following the sameprocedures as above (Controls 1 to 5). Table 2 also shows dataassociated with these Controls.

                                      TABLE 2                                     __________________________________________________________________________    Material Composition (Molar Ratio)                                            (A) Ferroelectric Inorganic Compound                                                                   (B) Inorganic Binder                                                                         Ratio of (A) and (B)                       (PFN)                                                                             (BCW)                                                                             MgO MnO                                                                              NiO  PbO    CuO WO.sub.3                                                                          A    B                                __________________________________________________________________________    Example                                                                       1    0.94                                                                              0.06                                                                              0.005                                                                             0.005                                                                            0.0025                                                                             0.9    0.1 --  0.8711                                                                             0.1289                           2    "   "   "   "  "    "      "   --  "    "                                3    "   "   "   "  "    0.7    0.3 --  0.8536                                                                             0.1464                           4    "   "   "   "  "    "      "   --  "    "                                5    1.0 0   "   "  "    0.9    0.1 --  0.8708                                                                             0.1292                           6    "   "   "   "  "    "      "   --  "    "                                7    "   "   "   "  "    0.7    0.3 --  0.8531                                                                             0.1469                           8    "   "   "   "  "    "      "   --  "    "                                9    0.95                                                                              0.05                                                                              "   "  "    0.9    0.1 --  0.8711                                                                             0.1289                           10   "   "   "   "  "    "      "   --  "    "                                11   "   "   "   "  "    0.7    0.3 --  0.8535                                                                             0.1465                           12   "   "   "   "  "      0.7692                                                                             --  0.2308                                                                            0.9395                                                                             0.0605                           13   "   "   "   "  "    0.8    0.2 --  0.8628                                                                             0.1372                           14   "   "   "   "  "      0.8569                                                                             --  0.1431                                                                            0.8790                                                                             0.1210                           15   "   "   "   "  "    "      --  "   "    "                                16   "   "   "   "  "      0.7692                                                                             --  0.2303                                                                            0.9395                                                                             0.0605                           Control                                                                       1    0.94                                                                              0.06                                                                              0.005                                                                             0.005                                                                            0.0025                                                                             PbO--CaO--B.sub.2 O.sub.3 --SiO.sub.2                                                        0.93 0.07                             2    "   "   "   "  "    "              0.95 0.05                             3    "   "   "   "  "    "              0.97 0.03                             4    "   "   "   "  "    PbO--CaO--SiO.sub.2 glass                                                                    0.75 0.25                             5    "   "   "   "  "    "              0.85 0.15                             __________________________________________________________________________    Material Preparation                   Characteristics of                     Pre-Sintering  Presence/Absence of                                                                         Pre-Sintering                                                                           Thick Film Capacitor                   Temperature of (A)                                                                           Pre-Sintering of (B)                                                                        Temperature of (B)                                                                      Dielectric                                                                          tan δ                           °C.                                                                              Mixing Only                                                                          Pre-Sintering                                                                        °C.                                                                              Constant                                                                            (× 10.sup.-2)              __________________________________________________________________________    Example                                                                       1    800       o      --     --        5000  2.02                             2    "         --     o      810       5000  1.99                             3    "         o      --     --        5500  1.40                             4    750       --     o      830       4300  1.10                             5    700       o      --     --        4000  1.05                             6    730       --     o      830       4100  1.90                             7    770       o      --     --        15000 0.50                             8    800       --     o      800       4400  1.05                             9    "         o      --     --        12000 0.89                             10   "         --     o      800       8000  0.97                             11   780       o      --     --        4500  1.03                             12   800       o      --     --        5900  0.68                             13   "         o      --     --        7000  1.13                             14   760       o      --     --        4100  1.09                             15   790       --     o      650       4000  1.11                             16   800       --     o      720       5100  1.01                             Control                                                                       1    800       o      --     --        50    5.3                              2    "         o      --     --        145   6.4                              3    "         o      --     --        270   4.6                              4    "         o      --     --        12.0  2.4                              5    "         o      --     --        13.0  0.83                             __________________________________________________________________________

As is apparent from the results shown in Table 2, the conventional thickfilm capacitors of Controls 1 to 5 have low dielectric constants of 12to 270, while the thick film capacitors of Examples 1 to 16 can providevery high dielectric constants of 4000 to 15,000.

<Effect of Aging at High Temperature>

Aging at high temperature of 900° C. for 10 minutes was performed 5times for the thick film capacitors obtained in Examples 2 and 9 andControl 3. Each time the aging process was completed, the dielectricconstant was measured, and a change in dielectric constant due to agingat high temperature was examined. The results shown in FIG. 4 wereobtained.

Aging at high temperature of 600° C. for 10 minutes was performed 6times for the thick film capacitors obtained in Example 13 and Control3. Each time the aging process was completed, the volume resistivity wasmeasured, and a change in volume resistivity due to aging at hightemperature was examined. The results shown in FIG. 5 were obtained.

As is apparent from the results shown in FIGS. 4 and 5, in the thickfilm capacitors of the examples, the dielectric constant can be improvedby 10% by aging at high temperature, and the volume resistivity can beincreased by 100 times. In contrast to this, in the thick filmcapacitors of the controls, when aging at high temperature is performed,both the dielectric constant and the volume resistivity are degraded.

In the aging at high temperature, any degradation of the thick filmcapacitors of the examples was not observed.

EXAMPLES 17-47 <A> Synthesis of Ferroelectric Inorganic Compound

As starting materials, PbO, Fe₂ O₃, WO₃, Nb₂ O₅, BaCO₃, CuO, MgCO₃,MnCO₃, NiO, SrCO₃, CaCO₃, ZrO₂, Co₂ O₃, ZnO, TiO₂, Sb₂ O₃, and Ta2O₅were used, and were formulated to obtain compositions corresponding toferroelectric compounds shown in Tables 3 and 4. Abbreviations such asPBZMT in Tables 3 and 4 indicate ferroelectric inorganic compounds shownin Table 1. The formulas corresponding to the ferroelectric inorganiccompounds and MnO as an additive were formulated at molar ratios shownin Tables 3 and 4. At this time, when a plurality formulas correspondingto ferroelectric inorganic compounds were used, they were used so that atotal of their molar ratios was 1.

After the formulated raw materials were wet-mixed by a ball mill andwere pre-sintered at a temperature of 700° to 800° C., they were thenground by the ball mill and dried, thus preparing ferroelectricinorganic compounds.

<B> Preparation of Inorganic Binder

PbO, CuO, WO₃, Nb₂ O₅, Sb₂ O₃, BaO, Fe₂ O₃, ZnO, and CaO were used asraw materials, and were weighed to obtain molar ratios shown in Tables 3and 4. The weighed materials were wet-mixed by a ball mill and dried,thereby obtaining eutectic compositions PbO-CuO, PbO-WO₃, PbO-Nb₂ O₅,PbO-Sb₂ O₃, PbO-CaO, PbO-Fe₂ O₃, PbO-ZnO, and BaO-WO₃. These eutecticcompositions were pre-sintered at a temperature of 700° to 830° C. andwere ground by a ball mill and dried to prepare inorganic binders.

<C> Preparation of Ferroelectric Paste

The ferroelectric inorganic compounds and inorganic binders prepared inprocesses <A> and <B> were formulated at ratios shown in Tables 3 and 4.28% by weight of terpineol as a solvent and 4% by weight ofethyl-cellulose as an organic binder were added to 68% by weight of eachformula, and were mixed, thereby preparing 30 types of ferroelectricpastes.

<D> Manufacturing of Thick Film Capacitor

Following the same procedures as in Examples 1 to 16, thick filmcapacitors as shown in FIG. 1 were manufactured using the aboveferroelectric pastes.

However, in Examples 21 and 23, the ferroelectric paste was printed as abuffer layer between the alumina substrate and the metal electrode andwas sintered.

The dielectric constant and dissipation factor (tanδ×10⁻²) at 1 kHz ofthe resultant thick film capacitors were measured. The results shown inTables 3 and 4 were obtained.

Note that for the sake of comparison, conventional thick film capacitorsusing glass as an inorganic binder were manufactured following the sameprocedures as above (Controls 6 to 10). Tables 3 and 4 also show dataassociated with these Controls.

                                      TABLE 3                                     __________________________________________________________________________    Material Composition (Molar Ratio)                                                 (A) Ferroelectric Inorganic                                                                           (B) Component of                                                                       Ratio of (A) and (B)                    Example                                                                            Compound Abbreviations and Added Amounts                                                              Inorganic Binder                                                                       A    B                                  __________________________________________________________________________    17   (PBZMT)                                                                              --    --   --    PbO Nb.sub.2 O.sub.5                                                                   0.90 0.10                                    1.0                     0.94                                                                              0.06                                         18   (PBZMT)                                                                              --    --   --    PbO ZnO                                               1.0                     0.89                                                                              0.11 0.93 0.07                               19   (PMN)  (PZN) (PT) --    PbO Nb.sub.2 O.sub.5                                  0.2    0.5   0.3        0.94                                                                              0.06 0.90 0.10                               20   (PMN)  (PZN) --   --    PbO ZnO  0.85 0.15                                    0.3    0.7              0.90                                                                              0.10                                         21   (PBZMT)                                                                              --    --   --    PbO Nb.sub.2 O.sub.5                                                                   0.87 0.13                                    1.0                     0.94                                                                              0.06                                         22   (PMN)  (PT)  --   --    PbO Nb.sub.2 O.sub.5                                                                   0.82 0.18                                    0.5    0.5              0.94                                                                              0.06                                         23   (PNiNFW)                                                                             --    --   MnO   PbO Nb.sub.2 O.sub.5                                                                   0.85 0.15                                    1.0                0.005                                                                              0.94                                                                              0.06                                         24   (PNiNFW)                                                                             --    --   MnO   PbO Fe.sub.2 O.sub.3                                                                   0.91 0.09                                    1.0                0.005                                                                              0.82                                                                              0.18                                         25   (PCoW) (PT)  --   --    PbO WO.sub.3                                                                           0.88 0.12                                    0.5    0.5              0.85                                                                              0.15                                         26   (PZNFWNi)                                                                            --    --   --    PbO ZnO  0.80 0.20                                    1.0                     0.9 0.1                                          27   (PNiWFN)                                                                             (BTZ) --   --    PbO WO.sub.3                                                                           0.85 0.15                                    0.7    0.3              0.85                                                                              0.15                                         28   (PMZFW)                                                                              --         MnO   PbO WO.sub.3                                                                           0.84 0.16                                    1.0               0.01  0.85                                                                              0.15                                         29   (PFW)  (PT)  (PZN)                                                                              --    PbO PbO  0.85 0.15                                    0.7    0.1   0.2        0.85                                                                              0.15                                         30   (PFW)  (PT)  (PZN)                                                                              --    PbO Nb.sub.2 O.sub.5                                                                   0.79 0.21                                    0.7    0.1   0.2        0.94                                                                              0.06                                         31   (PFW)  (PT)  --   --    PbO WO.sub.3                                                                           0.86 0.14                                    0.8    0.2              0.85                                                                              0.15                                         32   (PMnW) (PT)  (PNiN)                                                                             (PMnSb)                                                                             PbO Nb.sub.2 O.sub.5                                                                   0.83 0.17                                    0.6     0.29 0.1  0.01  0.94                                                                              0.06                                         33   (PMnW) (PT)  (PNiN)                                                                             (PMnSb)                                                                             PbO Sb.sub.2 O.sub.3                                                                   0.87 0.13                                    0.6     0.29 0.1  0.01  0.62                                                                              0.38                                         34   (PNiW) (PT)  (PMnTa)                                                                            --    PbO WO.sub.3                                                                           0.81 0.19                                    0.5     0.49  0.01      0.80                                                                              0.20                                         __________________________________________________________________________    Material Preparation                                                                       Presence/                                                                     Absence of              Characteristics of                       Pre-Sintering                                                                              Pre-Sintering of (B)                                                                    Pre-Sintering Thick Film Capacitor                     Temperature of                                                                             Mixing                                                                             Pre- Temperature of                                                                        Electrode                                                                           Dielectric                                                                          tan δ                        Example                                                                            (A) °C.                                                                        Only Sintering                                                                          (B) °C.                                                                        Material                                                                            Constant                                                                            (× 10.sup.-2)                __________________________________________________________________________    17   850     o    --   --      Pt    4200  1.50                               18   "       --   o    750     Ag    4500  1.05                               19   "       o    --   --      Pd    5000  2.31                               20   "       o    --   --      Ni    4800  1.90                               21   860     --   o    700     Ag--Pd                                                                              7000  1.99                               22   870     o    --   --      Pd    11000 1.86                               23   850     o    --   --      Ag--Pd                                                                              7100  2.20                               24   "       o    --   --      Ag--Pd                                                                              6500  4.00                               25   "       o    --   --      Ag    5100  2.02                               26   "       --   o    720     Ag--Pd                                                                              7500  3.15                               27   800     o    --   --      Ag--Pd                                                                              4000  2.87                               28   860     o    --   --      Ag--Pt                                                                              6000  2.50                               29   800     o    --   --      Ag--Pd                                                                              5100  2.02                               30   850     --   o    730     Ag--Pd                                                                              4800  1.89                               31   800     o    --   --      Ag--Pd                                                                              8000  2.61                               32   "       --   o    730     Ag--Pd                                                                              4000  1.90                               33   820     o    --   --      Ag--Pd                                                                              4000  2.30                               34   810     o    --   --      Ag--Pd                                                                              4000  2.11                               __________________________________________________________________________

                                      TABLE 4                                     __________________________________________________________________________    Material Composition (Molar Ratio)                                            (A) Ferroelectric Inorganic                                                                              (B) Component of                                                                             Ratio of (A) and (B)                Compound Abbreviations and Added Amounts                                                                 Inorganic Binder                                                                             A    B                              __________________________________________________________________________    Example                                                                       35   (PMW)  (PT)                                                                              (PZ) (PMnW)                                                                              PbO     WO.sub.3                                                                             0.86 0.14                                 0.66  0.323                                                                              0.007                                                                             0.01  0.90    0.10                                       36   (PMW)  (PT)                                                                              (PMnTa)                                                                            --    PbO     WO.sub.3                                                                             0.88 0.12                                 0.645 0.345                                                                             0.01       0.82    0.18                                       37   (PMW)  (PT)                                                                              (PMnF)                                                                             --    PbO     WO.sub.3                                                                             0.89 0.11                                 0.645 0.345                                                                             0.01       0.87    0.13                                       38   (PZN)  (PFN)                                                                             (PFW)                                                                              MnO   PbO     WO.sub.3                                                                             0.87 0.13                                 0.16  0.48                                                                              0.36 0.01  0.85    0.15                                       39   (PZN)  (PFN)                                                                             (PFW)                                                                              MnO   PbO     Nb.sub.2 O.sub.3                                                                     0.88 0.12                                 0.16  0.48                                                                              0.36 0.01  0.9     0.1                                        40   (PFN)  (PFW)                                                                             --   MnO   PbO     Nb.sub.2 O.sub.3                                                                     0.95 0.05                                0.7    0.3      0.01  0.9     0.1                                        41   (PFW)  (PFN)                                                                             (PMnN)                                                                             MnO   PbO     WO.sub.3                                                                             0.91 0.09                                0.3    0.69                                                                              0.01 0.01  0.91    0.09                                       42   (PFW)  (PFN)                                                                             (PMnTa)                                                                            MnO   PbO     WO.sub.3                                                                             0.87 0.13                                0.3    0.69                                                                              0.01 0.01  0.85    0.15                                       43   (SPT)  (PMW)                                                                             --   --    PbO     WO.sub.3                                                                             0.88 0.12                                0.4    0.6            0.84    0.16                                       44   (PCaMNNi)                                                                            --  --   --    PbO     Nb.sub.2 O.sub.5                                                                     0.86 0.14                                1.0                   0.92    0.08                                       45   (PCaMNNi)                                                                            --  --   --    PbO     CaO    0.87 0.13                                1.0                   0.85    0.15                                       46   (PCaMNNi)                                                                            --  --   --    PbO     WO.sub.3                                                                             0.89 0.11                                1.0                   0.85    0.15                                       47   (PCZMT)                                                                              --  --   --    PbO     ZnO    0.75 0.25                                                      0.96    0.4                                        Control                                                                       6    (PBZMT)                                                                              --   --  --    PbO--CaO--SiO.sub.2 glass                                                                    0.80 0.20                                1.0                                                                      7    (PBZMT)                                                                              --  --   --    PbO.SiO.sub.2 glass                                                                          0.89 0.11                                1.0                                                                      8    (PBZMT)                                                                              --  --   --    "              0.95 0.05                                1.0                                                                      9    (PBZMT)                                                                              --  --   --    PbO--SiO.sub.2 --BaO--Bi.sub.2 O.sub.3                                                       0.93s                                                                              0.07                                1.0                                                                      10   (PCaMN)                                                                              --  --   --    PbO--CaO--SiO.sub. 2 --Bi.sub.2 O.sub.3                                                      0.94 0.06                                1.0                   glass                                              __________________________________________________________________________    Material Preparation                     Characteristics of                   Pre-Sintering                                                                              Presence/Absence of                                                                         Pre-Sintering Thick Film Capacitor                 Temperature of                                                                             Pre-Sintering of (B)                                                                        Temperature of                                                                        Electrode                                                                           Dielectric                                                                          tan δ                         (A) °C.                                                                        Mixing Only                                                                          Pre-Sintering                                                                        (B) °C.                                                                        Material                                                                            Constant                                                                            (× 10.sup.-2)            __________________________________________________________________________    Example                                                                       35   800     o      --     --      Ag--Pd                                                                              4500  2.70                           36   "       o      --     --      "     5000  2.67                           37   "       o      --     --      Ag--Pt                                                                              6200  2.96                           38   "       o      --     --      Ag--Pd                                                                              8000  2.55                           39   "       --     o      730     "     7800  2.37                           40   "       --     o      "       "     9200  1.79                           41   830     o      --     --      "     8800  2.45                           42   "       o      --     --      "     8100  2.33                           43   800     o      --     --      "     4800  2.81                           44   840     --     o      730     Cu    5600  1.41                           45   "       --     o      "       "     5900  1.22                           46   "       o      --     --      "     5500  1.31                           47   900     o      --     --      Cu    5000  2.00                           Control                                                                       6    850     o      --     --      Ag--Pt                                                                               50   6.28                           7    "       o      --     --      "      550  3.50                           8    "       o      --     --      "      800  3.21                           9    "       o      --     --      Ag--Pd                                                                              2900  3.00                           10   900     o      --     --      "      700  2.45                           __________________________________________________________________________

As is apparent from the results shown in Tables 3 and 4, theconventional thick film capacitors of Controls 6 to 10 have lowdielectric constants of 12 to 2900, while the thick film capacitors ofExamples 17 to 47 can provide very high dielectric constants of 4000 to11000.

<Compatibility with Printed Resistor>

In Examples 1 to 46 and Controls 1 to 10, a resistor was formed on asingle substrate together with the thick film capacitor by the followingtwo methods using a commercially available resistor paste. In the firstmethod, a resistor paste layer was printed and sintered on an insulatingpaste layer formed on an upper metal paste layer. In the second method,a resistor paste was printed and sintered adjacent to the thick filmcapacitor to be in contact with the ferroelectric paste layer.

The resultant resistors were checked. In the case of Examples 1 to 46,with either method, a resistor having a desired resistance could beformed. In contrast to this, in the case of Controls 1 to 10, a resistorhaving a desired resistance could not be formed by either method. Thisis because in the Controls, glass contained in the ferroelectric pasteas a binder was diffused to the resistor paste layer during sintering.

EXAMPLES 48-53 <A> Synthesis of Ferroelectric Inorganic Compounds

PbO, Fe₂ O₃, WO₃, Nb₂ O₅, BaCO₃, and CuO were used as startingmaterials, and were formulated to obtain compositions corresponding toferroelectric compounds PFN and BCW shown in Table 1. The PFN and BCWformulas were mixed at molar ratios x:y (x+y=1) shown in Table 5.

Subsequently, the formulated raw materials were wet-mixed by a ballmill, and were pre-sintered at a temperature of 700° to 800° C. Thepre-sintered bodies were ground by a ball mill and dried to prepareferroelectric inorganic compounds.

<B> Preparation of Inorganic Binder

PbO, WO₃, CuO, Fe₂ O₃, Nb₂ O₅, and BaO were used as raw materials, andwere weighed to obtain molar ratios shown in Table 5. The weighedmaterials were wet-mixed by a ball mill and dried, thus obtainingeutectic compositions PbO-CuO, PbO-WO₃, PbO-Nb₂ O₅, PbO-Nb₂ O₅ -BaO-CuO,PbO-Nb₂ O₅ -WO₃, and PbO-WO₃ -CuO. The eutectic compositions weredirectly used as inorganic binders. The eutectic compositions were alsopre-sintered at a temperature of 600° to 1000° C., ground by a ballmill, and dried to be used as inorganic binders.

<C> Preparation of Ferroelectric Paste

The ferroelectric inorganic compounds and inorganic binders prepared inprocesses <A> and <B> were formulated at ratios shown in Table 5. 28% byweight of terpineol as a solvent and 4% by weight of ethyl-cellulose asan organic binder were added to 68% by weight of each formula, and weremixed, thereby preparing 6 types of ferroelectric pastes.

28% by weight of terpineol as a solvent and 4% by weight ofethyl-cellulose as an organic binder were added to 68% by weight of theferroelectric inorganic compound and were mixed, thereby preparingferroelectric pastes containing no inorganic binder.

<D> Manufacture of Thick Film Capacitor

The ferroelectric pastes containing inorganic binders, the ferroelectricpastes containing no inorganic binders and an Ag-Pb-based metal pastewere used to form multi-layered structures shown in FIG. 2 by a printmethod. The multi-layered structures were sintered at 900° C. for 10minutes using a belt furnace, thereby producing the thick filmcapacitors.

The dielectric constant and dissipation factor (tanδ×10⁻²) at 1 kHz ofthe resultant thick film condensers were measured. The results shown inTable 5 were obtained.

For the sake of comparison, a conventional thick film capacitor wasproduced using glass as an inorganic binder and omitting a ferroelectricpaste layer (14 in FIG. 2) containing no inorganic binder (Control 11).

A thick film capacitor was produced following the same procedures as inthe above examples while omitting a paste layer (14 in FIG. 2)containing no inorganic binder (References 1 and 2).

Table 5 also shows data associated with the control and references.

                                      TABLE 5                                     __________________________________________________________________________    Material Composition (Molar Ratio)                                            (A) Ferroelectric                     Material Preparation                    Inorganic Compound                              Pre-Sintering or              Abbreviations and            Ratio of Pre-Sintering                                                                           Glass Transition              Added Amounts   (B) Component of                                                                           (A) and (B)                                                                            Temperature of (A)                                                                      Temperature of (B)                 PFN   BCW  Inorganic Binder                                                                           A    B   °C.                                                                              °C.                    __________________________________________________________________________    Example                                                                       48   0.94  0.06 PbO:CuO = 0.9:0.1                                                                          0.8711                                                                             0.1289                                                                            800       No Pre-sintering              49   "     "    PbO:WO.sub.3 = 0.77:0.23                                                                   0.9395                                                                             0.0605                                                                            "         "                             50   "     "    PbO:Nb.sub.2 O.sub.5 = 0.94:0.06                                                           0.8900                                                                             0.1100                                                                            810       "                             51   0.95  0.05 PbO:Nb.sub.2 O.sub.5 :BaO:CuO =                                                            0.91 0.90                                                                              800       1000                                          0.88:0.06:0.02:0.04                                           52   "     "    PbO:Nb.sub.2 O.sub.5 :WO.sub.3 =                                                           0.85 0.15                                                                              790       Pre-sintering                                 0.90:0.06:0.04                   750                          53   "     "    PbO:WO.sub.3 :CuO =                                                                        0.88 0.12                                                                              800       No Pre-sintering                              0.90:0.09:0.01                                                Control                                                                       11   0.94  0.06 PbO-- CaO--B.sub.2 O.sub.3 --SiO.sub.2                                                     0.93 0.07                                                                              800       No Pre-sintering                              glass                                                          1   "     "    PbO:CuO = 0.9:0.1                                                                          0.89 0.11                                                                              "         No Pre-sintering               2   "     "    "            "    "   "         "                             __________________________________________________________________________    Formation Method of Ferroelectric Layer                                                    Number of                         Characteristics of             Number of    Layers of Com-                                                                        Ratio of Thickness for    Thick Film Capacitor                Layers of Only                                                                        ponent Mixture                                                                        A and A + B               Dielectric                                                                          tan δ                   (A) Component                                                                         of (A + B)                                                                            Layer Formation order                                                                      Electrode Material                                                                         Constant                                                                            (× 10.sup.-2)      __________________________________________________________________________    Example                                                                       48   1       2       A/(A + B) = 1                                                                              Ag--Pd only  13500 0.90                                          (A + B) · A · (A + B)                  49   1       2       A/(A + B) = 0.5                                                                            "            15000 0.91                                          (A + B) · A · (A + B)                  50   2       1       A/(A + B) = 1                                                                              "            13000 0.85                                          A · (A + B) · A                        51   2       3       A/(A + B) = 1.5                                                                            "            13100 1.20                                          (A + B) · A ·                                               (A + B) · A · (A + B)                  52   1       2       A/(A + B) = 1                                                                              "            15500 0.95                                          (A + B) · A · (A + B)                  53   2       3       A/(A + B) = 1                                                                              PbO (2 wt %),                                                                              15600 0.90                                          (A + B) · A ·                                                            WO.sub.3 (2 wt %)-                                               (A + B) · A · (A                                                         added Ag--Pb                                Control                                                                       11   0       1       --           Ag--Pd only    50  3.8                       1   0       1       --           "             8000 1.3                       2   0       1       --           PbO--B.sub.2 O.sub.3 --SiO.sub.2                                                            900s-                                                                              2.5                                                        added Ag--Pd                                __________________________________________________________________________

As is apparent from the results shown in Table 5, the conventional thickfilm capacitor of Control 11 has a low dielectric constant of 50, whilethe thick film capacitors of Examples 48 to 53 have extremely highdielectric constants of 13000 or higher. The values of these examplesare remarkably larger than dielectric constants of 8000 and 9000 ofReferences 1 and 2. This effect is caused by stacking and sinteringferroelectric pastes (14 in FIG. 2) containing no inorganic binder.

EXAMPLES 54-68 <A> Synthesis of Ferroelectric Inorganic Compound

PbO, Fe₂ O₃, WO₃, Nb₂ O₅, BaCO₃, CuO, MgCO₃, and NiO were used asstarting materials, and were formulated to obtain compositionscorresponding to ferroelectric inorganic compounds PFN and BCW shown inTable 1. The formulas corresponding to the ferroelectric inorganiccompounds and NiO, MgO, and MnO as additives were formulated to obtainmolar ratios shown in Table 6. In this case, as can be seen from thevalues in Table 6, x(PFN)-y(BCW) [x+y=1].

After the formulated raw materials were wet-mixed by a ball mill, thematerials were pre-sintered at a temperature of 700° to 800° C. and werefurther ground by a ball mill and dried, thereby preparing ferroelectricinorganic compounds.

<B> Preparation of Inorganic Binder

PbO, CuO, and WO₃ as raw materials were weighed to obtain molar ratiosshown in Table 6, and were wet-mixed by a ball mill and dried, thusobtaining eutectic compositions PbO-CuO and PbO-WO₃. After the eutecticcompositions were pre-sintered at a temperature of 600° to 830° C., theywere ground by a ball mill and dried to prepare inorganic binders.

<C> Preparation of Ferroelectric Paste

The ferroelectric inorganic compounds and inorganic binders prepared inprocesses <A> and <B> were formulated at the ratios shown in Table 6.28% by weight of terpineol as a solvent and 4% by weight ofethylcellulose as an organic binder were added to 68% by weight of eachformula and were mixed. As a result, 15 types of ferroelectric pasteswere prepared.

<D> Production of Tip Capacitor

An Ag-Pb-based metal paste, the above ferroelectric pastes, and theAg-Pb-based metal paste were sequentially printed and stacked on a 2"×2"alumina substrate, and the resultant structure was sintered at 900° C.for 10 minutes using a belt oven. Each sintered structure was cut intopieces, thereby manufacturing tip capacitors having the structure shownin FIG. 3.

The dielectric constant and dielectric loss tangent (tanδ×10⁻²) at 1 kHzof the resultant thick film capacitors were measured. The results shownin Table 6 were obtained.

For the sake of comparison, conventional thick film capacitors wereproduced using glass as an inorganic binder (Controls 12 to 16). A tipcapacitor was manufactured by the green sheet method (Control 17). Table6 also shows data associated with these controls.

                                      TABLE 6                                     __________________________________________________________________________    Material Composition (Molar Ratio)                                            (A) Ferroelectric Inorganic Compound                                                                      (B) Inorganic Binder                                                                         Ratio of (A) and (B)                    (PFN)                                                                              (BCW)                                                                              MgO MnO NiO  PbO  CuO  WO.sub.3                                                                           A    B                             __________________________________________________________________________    Example                                                                       54   0.94 0.06 0.005                                                                             0.005                                                                             0.0025                                                                             0.9  0.1  --   0.8711                                                                             0.1289                        55   "    "    "   "   "    "    "    --   "    "                             56   "    "    "   "   "    0.7  0.3  --   0.8536                                                                             0.1464                        57   "    "    "   "   "    "    "    --   "    "                             58   1.0  0    "   "   "    0.9  0.1  --   0.3708                                                                             0.1292                        59   "    "    "   "   "    "    "    --   "    "                             60   "    "    "   "   "    0.7  0.3  --   0.8531                                                                             0.1469                        61   "    "    "   "   "    "    "    --   "    "                             62   0.95 0.05 0.005                                                                             0.005                                                                             0.0025                                                                             0.9  0.1  --   0.3711                                                                             0.1289                        63   "    "    "   "   "    "    "    --   "    "                             64   "    "    "   "   "    0.7  0.3  --   0.3535                                                                             0.1465                        65   "    "    "   "   "      0.7692                                                                           --   0.2308                                                                             0.9395                                                                             0.0605                        66   "    "    "   "   "    0.8  0.2  --   0.8628                                                                             0.1372                        67   "    "    "   "   "      0.8569                                                                           --   0.1431                                                                             0.8790                                                                             0.1210                        68   "    "    "   "   "    "    --   "    "    "                             Control                                                                       12   0.94 0.06 0.005                                                                             0.005                                                                             0.0025                                                                             PbO--CaO--B.sub.2 O.sub.3 --SiO.sub.2                                                        0.93 0.07                          13   "    "    "   "   "    "              0.95 0.05                          14   "    "    "   "   "    "              0.97 0.03                          15   "    "    "   "   "    PbO--CaO--SiO.sub.2 glass                                                                    0.75 0.25                          16   "    "    "   "   "    "              0.85 0.15                          17   Tip Condenser by Green Sheet Method (Commercial Product)                 __________________________________________________________________________    Material Preparation               Characteristics of                         Pre-Sintering                                                                              Presence/Absence of                                                                         Pre-Sintering                                                                         Tip Capacitor                              Temperature of                                                                             Pre-Sintering of (B)                                                                        Temperature of                                                                        Dielectric                                                                          tan δ                                                                        Thickness of                         (A) °C.                                                                        Mixing Only                                                                          Pre-Sintering                                                                        (B) °C.                                                                        Constant                                                                            (× 10.sup.-2)                                                                Tip Capacitor                   __________________________________________________________________________    Example                                                                       54   800     o      --     --      5000  2.02 0.35                            55   "       --     o      810     5000  1.99 0.25                            56   "       o      --     --      5500  1.40 0.35                            57   750     --     o      830     4300  1.10 0.35                            58   700     o      --     --      4000  1.05 0.35                            59   730     --     o      830     4100  1.90 0.35                            60   770     o      --     --      7000  2.15 0.15                            61   800     --     o      800     4400  1.05 0.35                            62   "       o      --     --      6600  0.89 0.35                            63   "       --     o      800     6000  0.97 0.20                            64   780     o      --     --      4500  1.03 0.20                            65   800     o      --     --      5900  0.68 0.20                            66   "       o      --     --      7000  1.13 0.20                            67   760     o      --     --      4100  1.09 0.20                            68   790     --     o      650     4000  1.11 0.25                            Control                                                                       12   800     o      --     --      50    5.3  0.20                            13   "       o      --     --      145   6.4  0.25                            14   "       o      --     --      270   4.6  0.3                             15   "       o      --     --      12.0  2.4  0.3                             16   "       o      --     --      13.0  0.83 0.3                             17   Tip Condenser by Green Sheet Method (Commercial Product)                                                    10000 1.0  0.8                             __________________________________________________________________________

As is apparent from the results shown in Table 6, the conventional thickfilm capacitors of Controls 12 to 16 have low dielectric constants of 12to 270, while the thick film capacitors of Examples 54 to 68 haveextremely high dielectric constants of 4000 to 7000.

The thickness of the tip capacitor of Control 17 is 0.6 to 1.0 mm, whilethe thickness of the tip capacitors of Examples 54 to 68 is very small,i.e., 0.5 mm or less.

EXAMPLES 69-98 <A> Synthesis of Ferroelectric Inorganic Compound

PbO, Fe₂ O₃, WO₃, Nb₂ O₅, BaCO₃, CuO, MgCO₃, MnCO₃, NiO, SrCO₃, CaCO₃,ZrO₂, Co₂ O₃, ZnO, TiO₂, Sb₂ O₃, and Ta₂ O₅ were used as startingmaterials, and were formulated to obtain compositions corresponding toferroelectric inorganic compounds shown in Tables 7 and 8. Abbreviationssuch as PBZMT and the like in Tables 7 and 8 indicate ferroelectricinorganic compounds shown in Table 1. The formulas corresponding to theferroelectric inorganic compounds and MnO as an additive were formulatedat the molar ratios shown in Tables 7 and 8. In this case, when aplurality of types of formulas corresponding to the ferroelectricinorganic compounds were used, a total of the molar ratios was 1.

After the formulated raw materials were wet-mixed by a ball mill, theywere pre-sintered at a temperature of 700° to 800° C. and ground by aball mill and dried, thereby preparing ferroelectric inorganiccompounds.

<B> Preparation of Inorganic Binder

PbO, CuO, WO₃, Nb₂ O₅, Sb₂ O₅, BaO, Fe₂ O₃, ZnO, and CaO as rawmaterials were weighed to obtain the molar ratios shown in Tables 7 and8 and were wet-mixed by a ball mill. Thereafter, the mixture was dried.The resultant eutectic compositions PbO-CuO, PbO-WO₃, PbO-Nb₂ O₅,PbO-Sb₂ O₃, PbO-CaO, PbO-Fe₂ O₃, PbO-ZnO, and BaO-WO₃ were directly usedas inorganic binders. After these eutectic compositions werepre-sintered at a temperature of 700° to 830° C., they were ground by aball mill and dried to be used also as inorganic binders.

<C> Preparation of Ferroelectric Paste

The ferroelectric inorganic compounds and inorganic binders prepared inprocesses <A> and <B> were formulated at the molar ratios shown inTables 7 and 8. 28% by weight of terpineol as a solvent and 4% by weightof ethyl-cellulose as an organic binder were added to 68% by weight ofeach formula and were mixed. As a result, 30 types of ferroelectricpastes were prepared.

<D> Manufacture of Tip Capacitor

Each electrode metal paste shown in Tables 7 and 8, each ferroelectricpaste obtained in process <C>, and a metal paste were sequentiallyprinted and stacked on a 2"×2" alumina substrate, and the resultantstructure was sintered at 900° C. for 10 minutes using a belt oven. Eachsintered structure was cut into pieces, thereby producing tip capacitorshaving the structure shown in FIG. 3.

The dielectric constant and dissipation factor (tanδ×10⁻²) at 1 kHz ofthe resultant thick film capacitors were measured. The results shown inTables 7 and 8 were obtained.

For the sake of comparison, conventional thick film capacitors wereproduced using glass as an inorganic binder (Controls 18 to 22). Tables7 and 8 also show data associated with these controls.

                                      TABLE 7                                     __________________________________________________________________________    Material Composition (Molar Ratio)                                            (A) Ferroelectric Inorganic Compound Abbreviations and                                                         (B) Component of                                                                        Ratio of (A) and (B)               Added Amounts                    Inorganic Binder                                                                        A     B                            __________________________________________________________________________    Example                                                                       69   (PBZMT)  --    --    --     PbO  Nb.sub.2 O.sub.5                                                                   0.90  0.10                              1.0                         0.94 0.06                                    70   (PBZMT)  --    --    --     PbO  ZnO  0.93  0.07                              1.0                         0.89 0.11                                    71   (PMN)    (PZN) (PT)  --     PbO  Nb.sub.2 O.sub.5                                                                   0.90  0.10                              0.2      0.5   0.3          0.94 0.06                                    72   (PMN)    (PZN) --    --     PbO  ZnO  0.85  0.15                              0.3      0.7                0.90 0.10                                    73   (PBZMT)  --    --    --     PbO  Nb.sub.2 O.sub.5                                                                   0.87  0.13                              1.0                         0.94 0.62                                    74   (PMN)    (PT)  --    --     PbO  Nb.sub.2 O.sub.5                                                                   0.82  0.18                              0.5      0.5                0.94 0.62                                    75   (PNiNFW) --    --    MnO    PbO  Nb.sub.2 O.sub.5                                                                   0.85  0.15                              1.0                   0.005 0.94 0.62                                    76   (PNiNFW) --    --    MnO    PbO  Fe.sub.2 O.sub.3                                                                   0.91  0.09                              1.0                   0.005 0.82 0.18                                    77   (PCoW)   (PT)  --    --     PbO  WO.sub.3                                                                           0.88  0.12                              0.5      0.5                0.85 0.15                                    78   (PZNFWNi)                                                                              --    --    --     PbO  ZnO  0.80  0.20                              1.0                         0.9  0.1                                     79   (PNiWFN) (BTZ) --    --     PbO  WO.sub.3                                                                           0.85  0.15                              0.7      0.3                0.85 0.15                                    80   (PMZFW)  --          MnO    PbO  WO.sub.3                                                                           0.84  0.16                              1.0                  0.01   0.85 0.15                                    81   (PFW)    (PT)  (PZN) --     PbO  WO.sub.3                                                                           0.85  0.15                              0.7      0.1   0.2          0.85 0.15                                    82   (PFW)    (PT)  " --  PbO    Nb.sub.2 O.sub.5                                                                   0.79 0.21                                    0.7      0.1   0.2          0.94 0.06                                    83   (PFW)    (PT)  --    --     PbO  WO.sub.3                                                                           0.86  0.14                              0.8      0.2                0.85 0.15                                    84   (PMnW)   (PT)  (PNiN)                                                                              (PMnSb)                                                                              PbO  Nb.sub.2 O.sub.5                                                                   0.83  0.17                              0.6      0.29  0.1   0.01   0.94 0.06                                    85   (PMnW)   (PT)  (PNiN)                                                                              (PMnSb)                                                                              PbO  Sb.sub.2 O.sub.3                                                                   0.87  0.13                              0.6      0.29  0.1   0.01   0.62 0.38                                    86   (PNiW)   (PT)  (PMnTa)                                                                             --     PbO  WO.sub.3                                                                           0.81  0.19                              0.5      0.49  0.01         0.80 0.20                                    __________________________________________________________________________    Material Preparation                                                                       Presence/                                                                     Absence of                                                                    Pre-Sintering          Characteristics of                        Pre-Sintering                                                                              of (B)   Pre-Sintering Tip Capacitor                                  Temperature of                                                                        Mixing                                                                            Pre- Temperature                                                                          Electrode                                                                            Dielectric                                                                          tan δ                                                                        Thickness of                   Example                                                                            (A) °C.                                                                        Only                                                                              Sintering                                                                          of (B) °C.                                                                    Material                                                                             Constant                                                                            (× 10.sup.-2)                                                                Tip Capacitor                  __________________________________________________________________________    69   850     o   --   --     Pt     4200  1.50 0.25                           70   "       --  o    750    Ag     4500  1.05 0.26                           71   "       o   --   --     Pd     5000  2.31 0.21                           72   "       o   --   --     Ni     4800  1.90 0.25                           73   860     --  o    700    Ag--Pd 7000  1.99 0.25                           74   870     o   --   --     Pd     11000 1.86 0.25                           75   850     o   --   --     Ag--Pd 7100  2.20 0.20                           76   "       o   --   --     "      6500  4.00 0.20                           77   "       o   --   --     Ag     5100  2.02 0.20                           78   "       --  o    720    Ag--Pd 7500  3.15 0.20                           79   800     o   --   --     "      4000  2.87 0.30                           80   860     o   --   --     Ag--Pt 6000  2.50 0.30                           81   800     o   --   --     Ag--Pd 5100  2.02 0.21                           82   850     --  o    730    "      4800  0.89 0.19                           83   800     o   --   --     "      8000  2.61 0.19                           84   "       --  o    730    "      4000  1.90 0.20                           85   820     o   --   --     "      4000  2.30 0.20                           86   810     o   --   --     "      4000  2.11 0.20                           __________________________________________________________________________

                                      TABLE 8                                     __________________________________________________________________________    Material Composition (Molar Ratio)                                            (A) Ferroelectric Inorganic Compound Abbreviations and                                                                           Ratio of (A) and (B)       Added Amounts                     (B) Component of Inorganic                                                                     Ainder                                                                              B                    __________________________________________________________________________    Example                                                                       87    (PMW)    (PT)  (PZ)  (PMnW) PbO     WO.sub.3 0.86  0.14                        0.66     0.323                                                                               0.007                                                                              0.01   0.90    0.10                                88    (PMW)    (PT)  (PMnTa)                                                                             --     PbO     WO.sub.3 0.88  0.12                        0.645    0.345                                                                              0.01         0.82    0.18                                89    (PMW)    (PT)  (PMnF)                                                                              --     PbO     WO.sub.3 0.89  0.11                        0.645   0.345 0.01         0.87    0.13                                90    (PZN)    (PFN) (PFW) MnO    PbO     WO.sub.3 0.87  0.13                        0.16     0.48 0.36  0.01   0.85    0.15     0.87  0.13                 91    (PZN)    (PFN) (PFW) MnO    PbO     Nb.sub.2 O.sub.3                                                                       0.88  0.12                        0.16     0.48 0.36  0.01   0.9     0.1                                 92    (PFN)    (PFW) --    MnO    PbO     Nb.sub.2 O.sub.3                                                                       0.95  0.05                       0.7      0.3         0.01   0.9     0.1                                 93    (PFW)    (PFN) (PMnN)                                                                              MnO    PbO     WO.sub.3 0.91  0.09                       0.3       0.69 0.01  0.01   0.91    0.09                                94    (PFW)    (PFN) (PMnTa)                                                                             MnO    PbO     WO.sub.3 0.87  0.13                       0.3       0.69 0.01  0.01   0.85    0.15                                95    (SPT)    (PMW) --    --     PbO     WO.sub.3 0.88  0.12                       0.4      0.6                0.84    0.16                                96    (PCaMNNi)                                                                              --    --    --     PbO     Nb.sub.2 O.sub.5                                                                       0.86  0.14                       1.0                         0.92    0.08                                97    (PCaMNNi)                                                                              --    --    --     PbO     CaO      0.87  0.13                       1.0                         0.85    0.15                                98    (PCaMNNi)                                                                              --    --    --     PbO     WO.sub.3 0.89  0.11                       1.0                         0.85    0.15                                Control                                                                       18    (PBZMT)  --    --    --     PbO--CaO--SiO.sub.2 glass                                                                      0.80  0.20                       1.0                                                                     19    (PBZMT)  --    --    --     PbO.SiO.sub.2 glass                                                                            0.89  0.11                       1.0                                                                     20    (PBZMT)  --    --    --     PbO.SiO.sub.2 glass                                                                            0.89  0.05                 21    (PBZMT)  --    --    --     PbO--SiO.sub.2 --BaO--Bi.sub.3 O.sub.3                                        glass            0.93  0.07                       1.0                                                                     22    (PCaMN)  --    --    --     PbO--CaO--SiO.sub.2 --Bi.sub.3 O.sub.3                                        glass            0.94  0.06                        1.01                                                                   __________________________________________________________________________    Material Preparation                         Characteristics of               Pre-Sintering  Presence/Absence of                                                                         Pre-Sintering   Tip Capacitor                    Temperature of (A)                                                                           Pre-Sintering of (B)                                                                        Temperature of (B)                                                                      Electrode                                                                           Dielectric                                                                          tan δ                                                                        Thickness of               °C.                                                                              Mixing Only                                                                          Pre-Sintering                                                                        °C.                                                                              Material                                                                            Constant                                                                            (× 10.sup.-2)                                                                Tip                   __________________________________________________________________________                                                            Capacitor             Example                                                                       87   800       o      --     --        Ag--Pd                                                                              4500  2.70 0.25                  88   "         o      --     --        "     5000  2.67 0.20                  89   "         o      --     --        Ag--Pt                                                                              6200  2.96 0.20                  90   "         o      --     --        Ag--Pd                                                                              8000  2.55 0.25                  91   "         --     o      730       "     7800  2.37 0.25                  92   "         --     o      "         "     9200  1.79 0.25                  93   830       o      --     --        "     8800  2.45 0.25                  94   "         o      --     --        "     8100  2.33 0.25                  95   800       o      --     --        "     4800  2.81 0.25                  96   840       --     o      730       Cu    5600  1.41 0.25                  97   "         --     o      "         "     5900  1.22 0.25                  98   "         o      --     --        "     5500  1.31 0.25                  Control                                                                       18   850       o      --     --        Ag--Pt                                                                               50   6.28 0.25                  19   "         o      --     --        "      550  3.50 0.25                  20   "         o      --     --        "      800  3.21 0.30                  21   "         o      --     --        Ag--Pd                                                                              2900  3.00 0.30                  22   900       o      --     --        "      700  2.45 0.30                  __________________________________________________________________________

As is apparent from the results shown in Tables 7 and 8, theconventional thick film capacitors of Controls 18 to 22 have lowdielectric constants of 50 to 2900, while the thick film capacitors ofExamples 69 to 98 have extremely high dielectric constants of 4000 to11000.

As has been described with reference to Control 17, the thickness of thetip capacitor formed by the green sheet method is 0.6 to 1.0 mm, whilethe thickness of the tip capacitors of Examples 69 to 98 is very small,i.e., 0.5 mm or less.

As described above, the thick film capacitor of the present inventionhas a high degree of sintering, a good dielectric characteristic, andhigh moisture and migration resistances.

In addition, since the thick film capacitor of the present invention iscompact and thin, it is advantageous for packaging, and the number ofproduction steps can be reduced.

What is claimed is:
 1. A thick film capacitor comprising:(a) a sinteredlayer of a ferroelectric material consisting essentially of at least oneferroelectric inorganic compound having a perovskite structure and aninoranic binder for sintering said at least one ferroelectric inorganiccompound without destroying the perovskite structure thereof, saidinorganic binder having a eutectic composition which experiences aliquid phase at a temperature lower than the sintering temperature ofsaid at least one ferroelectric inorganic compound; and (b) at least oneelectrode formed on each surface of said sintered layer of theferroelectric material.
 2. A capacitor according to claim 1, whereinsaid inorganic binder is present at grain boundaries of saidferroelectric inorganic compounds in said sintered layer of theferroelectric material.
 3. A capacitor according to claim 1, whereinsaid inorganic binder is diffused in crystals of said ferroelectricinorganic compounds in said sintered layer of the ferroelectricmaterial.
 4. A capacitor according to claim 1, wherein said inorganicbinder is present at grain boundaries and in crystals of saidferroelectric inorganic compounds in said sintered layer of theferroelectric material.
 5. A capacitor according to claim 1, whereinsaid ferroelectric inorganic compounds are selected from the groupconsisting of the following compounds:Pb(Fe_(1/2) Nb_(1/2))O₃-Ba(Cu_(1/2) W_(1/2))O₃, BaTiO₃, PbTiO₃, and (Pb,Ba){(Zn_(1/3)Nb_(2/3))(Mg_(1/3) Nb_(2/3))Ti}O₃.
 6. A capacitor according to claim 1,wherein said inorganic binder is selected from the group consisting ofthe following eutectic compositions:PbO-CuO, PbO-WO₃, PbO-Nb₂ O₅,PbO-Fe₂ O₃, PbO-ZnO, PbO-TiO₂, PbO-CaO, PbO-Sb₂ O₃, BaO-WO₃, Nb₂ O₃-TiO₂, TiO₂ -MgO, and PbO-MgO.
 7. A capacitor according to claim 6,wherein said inorganic binder is selected from the group consisting ofcompositions which are converted to eutectic compositions by oxidationduring sintering.
 8. A capacitor according to claim 1, wherein saidsintered layer of the ferroelectric material comprises a central layerhaving a small content of said inorganic binder and layers formed on andunder said central layer and having a large content of said inorganicbinder.
 9. A thick film capacitor comprising:(a) a first metal electrodelayer formed on an insulating substrate; (b) a sintered layer of aferroelectric material directly stacked on said first metal electrodelayer and consisting essentially of at least one ferroelectric inorganiccompound having a perovskite structure and an inorganic binder forsintering said at least one ferroelectric inorganic compound withoutdestroying the perovskite structure thereof, said inorganic binder hvinga eutectic composition which experiences a liquid phase at a temperaturelower than the sintering temperature of said at least one ferroelectricinorganic compound; and (c) a second metal electrode layer directlyformed on said sintered layer of a ferroelectric material sandwichedbetween said insulating substrate and said first metal electrode layer.10. A capacitor according to claim 9, further comprising a sinteredlayer of a ferroelectric material sandwiched between said insulatingsubstrate and said first metal electrode layer.
 11. A thick filmcapacitor comprising:(a) a first metal electrode layer formed on aninsulating substrate; (b) a sintered layer of a ferroelectric materialdirectly stacked on said first metal electrode layer and consistingessentially of at least one ferroelectric inorganic compound having aperovskite structure and an inorganic binder for sintering said at leastone ferroelectric inorganic compound without destroying the perovskitestructure thereof, said inorganic binder having a eutectic compositionwhich experiences a liquid phase at a temperature lower than thesintering temperature of said at least one ferroelectric inorganiccompound; and (c) a second metal electrode layer directly formed on saidsintered layer of the ferroelectric material, and wherein said thickfilm capacitor is cut into a tip having a desired size.
 12. A capacitoraccording to claim 11, wherein at least one multilayered structureconsisting of said sintered layer of the ferroelectric material and saidsecond metal electrode layer is stacked on said second metal electrodelayer.
 13. A capacitor according to claim 11, further comprising asintered layer of a ferroelectric material sandwiched between saidinsulating substrate and said first metal electrode layer.
 14. A thickfilm capacitor manufactured by the process comprising the steps of:(a)forming a first metal paste layer on an insulating substrate; (b)stacking on said first metal paste layer a ferroelectric paste layerconsisting essentially of at least one ferroelectric inorganic compoundhaving a perovskite structure, an inorganic binder for sintering said atleast one ferroelectric inorganic compound without destroying theperovskite structure thereof, said inorganic binder having a eutecticcomposition which experiences a liquid phase at a temperature lower thanthe sintering temperature of said ferroelectric compound, at least oneorganic binder and a solvent; (c) forming a second metal paste layerdirectly stacked on said ferroelectric paste layer; and (d) sinteringthe laminate formed at steps (a) to (c) at a temperature lower than thesintering temperature of said ferroelectric compound.
 15. A thick filmcapacitor manufactured by the process comprising the steps of:(a)forming a first metal paste layer on an insulating substrate; (b)stacking on said first metal paste layer a ferroelectric paste layerconsisting essentially of at least one ferroelectric inorganic compoundhaving a perovskite structure, an inorganic binder for sintering said atleast one ferroelectric inorganic compound without destroying theperovskite structure thereof, said inorganic binder having a eutecticcomposition which experiences a liquid phase at a temperature lower thanthe sintering temperature of said ferroelectric compound, at least oneorganic binder and a solvent; (c) forming a second metal paste layerdirectly stacked on said ferroelectric paste layer; (d) sintering thelaminate formed at steps (a) to (c) at a temperature lower than thesintering temperature of said ferroelectric compound, and (e) performingaging at high temperatures.